Veetle: Support Shortened URLs
Merge pull request #317 from athoik/veetle-short

Veetle: Support Shortened URLs
Add StreamIOIterWrapper, a file-like interface to a iterator.
Use res.iter_content() instead of res.raw.

Since res.raw is a raw file object it does
not handle decoding gzip, res.iter_content()
is the proper way to stream chunks.

Resolves #269.
plugins.ustreamtv: Improve initial load of UHS streams.

Attempts to start at 3 chunks from the end instead of the
last chunk. Since new chunks usually takes a few seconds
to appear this improves initial buffering speed and
playback experience.
plugins.youtube: Fake user agent on HLS streams.

Resolves #319.
utils: Safer verifyjson.
plugins.mlgtv: Update for API changes.

Resolves #320.
Update CHANGELOG.rst.
Release version 1.7.5.
Merge branch 'release/1.7.5' into develop